MODELING OF ONE-DIMENSIONAL UNSTEADY OPEN CHANNEL FLOWS IN INTERACTION WITH RESERVOIRS, DAMS AND HYDROPOWER PLANT OBJECTS

A number of existing software solutions are used to model one-dimensional unsteady openchannel flow using the standard boundary and initial conditions. Internal boundary conditions are two flow trajectories, related by special conditions and each is associated with two equations describing the water flow. The special conditions include the matrix formulation of limitations that apply to the flow inside the two connected trajectories. Branching, pipe joints and flow over the weir are some of the modeling tasks usually solved. This paper presents the algorithms used for the solution of the complex case of hydropower plant objects as internal boundary cases. The complexity of the problem lies in the fact that the hydropower plant is managed according to the electricity generation demand which is dependent both upon the upstream and downstream water levels, as well as the discharge. Since all state values are coupled and determined as system solutions, the algorithm leads to an iterative procedure of solving a system of non-linear equations. Software used in solving the standard, complete, dynamic equations of flow in one-dimensional unsteady open channel flow and through the control structures, was adopted as the foundation applied in simulation of the “Iron Gate” (“Đerdap” in Serbian; “Portile de Fier” in Romanian) system, with detailed modeling of three objects of the hydropower plants “Iron Gate 1”, “Iron Gate 2” and “Gogoš”.